Nonradiative dielectric line apparatus and instrument for measuring characteristics of a circuit board

ABSTRACT

The ease of mounting a circuit board on a nonradiative dielectric line is improved, the degree of freedom of conductor film patterns formed on the circuit board is increased, and the degree of integration can be easily increased to fit within a small size. Dielectric strips are provided between the two conductor plates positioned in parallel to each other, and a circuit board is positioned parallel to the conductor plates. The conductor patterns on the circuit board and the transmission waves of the nonradiative dielectric line are electromagnetically coupled to each other.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus employing a nonradiativedielectric line and, more particularly, to an apparatus suitable for anintegrated circuit for use in a millimetric-wave band or a microwaveband.

2. Description of the Related Art

FIGS. 26(A), 26(B) and 26(C) are sectional views illustrating theconstructions of three types of a conventional nonradiative dielectricline (an NRD wave guide). FIG. 26(A) shows what is commonly called anormal-type nonradiative dielectric line in which a dielectric strip 100is disposed between conductors 101 and 102 disposed substantiallyparallel to each other. FIG. 26(B) shows what is commonly called agrooved-type nonradiative dielectric line in which a groove is formed ineach of the conductors 101 and 102, and the dielectric strip 100 isfitted into the grooves. FIG. 26(C) shows what is commonly called awinged-type nonradiative dielectric line comprising conductors 101 and102 which contact plane-shaped wing portions 103' and 104' of dielectricstrips 103 and 104, the dielectric strips 103 and 104 face each otheracross a gap.

In such a nonradiative dielectric line, transmission loss is reduced bymaking the spacing y between the conductors to be a half-wavelength ofthe propagation wavelength of the electromagnetic wave, thus suppressingradiation at a bent portion or a noncontinuous portion.

FIG. 27 shows an example of a conventional apparatus employing such anonradiative dielectric line. Referring to FIG. 27, reference numeral105 denotes a circuit board on which electrodes 106 and 107 are formedand a beam-lead diode 108 is mounted. With such a placement of a circuitboard having electrodes formed thereon and having electronic partsmounted thereon on the end surface of the dielectric strip 100, in thisexample, the beam-lead diode 108 will be coupled to the electromagneticwave which is propagated through the dielectric strip 100.

FIG. 28 shows an example in which a nonradiative dielectric line isapplied to a Gunn oscillator. Referring to FIG. 28, reference numeral109 denotes a strip line formed on the circuit board 105. Referencenumeral 110 denotes a Gunn diode incorporated into the block, with itselectrodes being connected to the strip line 109. The circuit board 105,being positioned in parallel to the end surface of the dielectric strip100 (in a direction perpendicular to a direction parallel to the lengthof the dielectric strip), causes the electromagnetic wave propagatedthrough the dielectric strip 100 and the strip line 109 to beelectromagnetically coupled to each other.

As described above, in the conventional apparatus employing anonradiative dielectric line, in order to couple a dielectric strip to aconductor line on a circuit board, a circuit board is positioned on theend surface of the dielectric strip, and the circuit board is positionedperpendicular to the length of the dielectric strip. However, in such aconstruction, it is difficult to fixedly secure the circuit board withinthe apparatus, and since the circuit board is likely to be inclined, thecircuit board cannot be easily mounted. Further, since in thisconstruction which a circuit board is disposed between two conductors,only long, narrow strip-shaped circuit boards can be used, and thepatterns of conductor lines or the like that can be formed are limited.For this reason, it is not possible to form an integrated circuit of arelatively large-scale circuit with a small number of parts.

Further, with the dielectric strip being disposed between the conductorsand an integrated circuit is formed together with the circuit board,adjustments cannot be performed with a single circuit board. Therefore,adjustment operations must be repeatedly performed. For example,characteristics are measured with the circuit board incorporated intothe nonradiative dielectric line, the circuit board is removed duringthe adjustment, and the circuit board is assembled again after theadjustment and its characteristics are again measured. Thus, theadjustment operations are complicated and inefficient.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a nonradiativedielectric line apparatus in which the ease of mounting of the circuitboard in the nonradiative dielectric line apparatus is improved, thedegree of freedom of conductor film patterns to be formed on the circuitboard is increased, and the degree of integration can be easilyincreased to fit within a small size.

It is another object of the present invention to provide an instrumentfor measuring characteristics of a circuit board, in which instrumentcharacteristic measurement and adjustments are made possible with asingle circuit board.

In the nonradiative dielectric line apparatus according to one aspect ofthe present invention, in order to improve the ease of mounting of acircuit board in a nonradiative dielectric line, to increase the degreeof freedom of patterns of a conductor film to be formed on the circuitboard, and to increase the degree of integration within a small size, acircuit board having a conductor film or a circuit element together witha conductor film provided thereon is disposed between two conductors andsubstantially parallel to the conductors, and the conductor film or thecircuit element provided on the circuit board is brought close to or ismade to penetrate into the dielectric strip in order to couple theconductor film or the circuit element to the nonradiative dielectricline. With this construction, the conductor film or the circuit elementon the circuit board is coupled to the electromagnetic wave which ispropagated through the dielectric strip, and thus a nonradiativedielectric line apparatus serving as an integrated circuit into which anonradiative dielectric line and a circuit board are incorporated can beobtained. At this point, since the circuit board is disposed between twoconductors to be substantially parallel to the two conductors, the easeof mounting of the circuit board is high because, for example, when twoconductors are disposed in parallel to each other, the circuit board ispositioned so as to be interposed between the conductors or positionedalong the conductors. Further, since the circuit board is positionedalong the two conductors, it is possible to provide a number ofconductor films or circuit elements together with the conductor films byusing a large-area circuit board, and thus an apparatus having a highintegration can be easily obtained.

In the nonradiative dielectric line apparatus according to anotheraspect of the present invention, in order for the nonradiativedielectric line apparatus to be used as an oscillator, an oscillationelement, and a conductor line for transmitting oscillation signals ofthe oscillation element are provided on the circuit board, and theconductor line is brought close to or is made to penetrate into thedielectric strip in order to transmit the oscillation signals to thenonradiative dielectric line. With this construction, the oscillationsignals of the oscillation element are transmitted to the nonradiativedielectric line, and thus a nonradiative dielectric line apparatusserving as an integrated circuit into which an oscillator together witha nonradiative dielectric line are incorporated can be obtained.

In the nonradiative dielectric line apparatus according to a furtheraspect of the present invention, in order for the nonradiativedielectric line apparatus to be used as an attenuator or terminator, aresistor film is formed on the circuit board, and the resistor film isbrought close to or is made to penetrate into the dielectric strip inorder to attenuate the electromagnetic wave to be propagated through thenonradiative dielectric line. With this construction, since the energyof the electromagnetic wave of a mode having electric-field componentsparallel to the resistor film, namely, an LSM mode, is converted intoJoule heat in the resistor film, the electromagnetic wave which ispropagated through the nonradiative dielectric line is attenuated, andthus a nonradiative dielectric line apparatus serving as an integratedcircuit in which an attenuator or a terminator is incorporated togetherwith a nonradiative dielectric line can be obtained.

In the nonradiative dielectric line apparatus according to a stillfurther aspect of the present invention, in order for the nonradiativedielectric line apparatus to be used as a directional coupler, two ofthe dielectric strips are provided side by side to form two nonradiativedielectric lines, a plurality of conductor film patterns are provided onthe circuit board at intervals of 1/4 waveguide length, the plurality ofconductor film patterns provided between the two dielectric strips, andthe plurality of conductor film patterns are brought close to or aremade to penetrate into the two dielectric strips in order to couple thetwo nonradiative dielectric lines. With this construction, since twodielectric strips are disposed between two conductors, two nonradiativedielectric lines are formed, and the two nonradiative dielectric linesare coupled to each other via a plurality of conductor film patterns.For example, in a case in which three strip lines a, b and c areprovided for two dielectric strips as shown in FIG. 14, the waves whichenter from (1) exit in part to (2), and a remaining part of the wavesleak to a dielectric strip on the right through the three strip lines a,b and c. At this time, since all waves which exit to (4) and which passthrough any strip line are out of phase by the same phase, the waves aresynthesized at the same phase. However, regarding the waves which exitto (3), the waves which pass through the rear strip line (e.g., a stripline b) are delayed in comparison with the waves which pass through thefront strip line (e.g., a strip line a) by a phase corresponding toλ/4+λg/4=λg/2. Therefore, the synthesized waves cancel each other, andno wave appears in the direction of (3). As a result, the nonradiativedielectric line apparatus works as a directional coupler.

In an instrument for measuring characteristics of a circuit boardaccording to a still further aspect of the present invention, in orderfor the instrument to be able to measure the characteristics of acircuit board, there are provided two conductors positioned in parallelto each other, a dielectric strip disposed between the two conductors,and a circuit board housing section for housing the circuit boardaccording to the above-mentioned aspects of the invention, which circuitboard housing section is disposed between the two conductors, whereinthe characteristics of the circuit board are measured via the dielectricstrip with the circuit board being housed in the circuit board housingsection. With this construction, by housing a circuit board set forth inany one of the above-mentioned aspects of the invention in the circuitboard housing section provided between two conductors positionedparallel to each other, a nonradiative dielectric line apparatuscomprising a circuit board is formed. Therefore, it is possible tomeasure the characteristics of the circuit board by measuring theelectromagnetic waves propagated through the dielectric strip via thedielectric strip. Further, after the fact is confirmed thatpredetermined characteristics can be obtained, or after the adjustmentsof the circuit board are performed until predetermined characteristicsare obtained, a nonradiative dielectric line apparatus having desiredcharacteristics can be obtained by incorporating the circuit board intoan actual nonradiative dielectric line.

The above and further objects, aspects and novel features of theinvention will become more apparent from the following detaileddescription when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a nonradiative dielectric line apparatusaccording to a first embodiment of the present invention;

FIG. 2 is an exploded perspective view of the nonradiative dielectricline apparatus shown in FIG. 1;

FIG. 3 is a perspective view of a nonradiative dielectric line apparatusaccording to a second embodiment of the present invention;

FIG. 4 is an exploded perspective view of the nonradiative dielectricline apparatus shown in FIG. 3;

FIGS. 5(A) and 5(B) are partial perspective views illustrating therelationship between the electromagnetic-field distribution of thenonradiative dielectric line and the conductor film patterns on thecircuit board;

FIGS. 6(A) and 6(B) show the construction of a nonradiative dielectricline apparatus for use as an oscillator according to a third embodimentof the present invention;

FIG. 7 shows the construction of a nonradiative dielectric lineapparatus for use as an oscillator according to a fourth embodiment ofthe present invention;

FIGS. 8(A) and 8(B) show the construction of a nonradiative dielectricline apparatus for use as an oscillator according to a fifth embodimentof the present invention;

FIG. 9 shows the construction of a nonradiative dielectric lineapparatus for use as a terminator according to a sixth embodiment of thepresent invention;

FIG. 10 shows the construction of a nonradiative dielectric lineapparatus for use as a terminator according to a seventh embodiment ofthe present invention;

FIGS. 11(A) and 11(B) show the construction of a nonradiative dielectricline apparatus for use as a terminator according to an eighth embodimentof the present invention;

FIGS. 12(A) and 12(B) show the construction of a nonradiative dielectricline apparatus for use as an attenuator according to a ninth embodimentof the present invention;

FIG. 13 shows the construction of a nonradiative dielectric lineapparatus for use as a directional coupler according to a tenthembodiment of the present invention;

FIG. 14 shows the relationship between a dielectric strip and a stripline in the directional coupler;

FIGS. 15(A) and 15(B) show the construction of an FM-CW radar front-endportion according to an eleventh embodiment of the present invention;

FIG. 16 shows an equivalent circuit of the FM-CW radar front-end portionshown in FIG. 15;

FIGS. 17(A) and 17(B) show the construction of an instrument formeasuring characteristics of a circuit board for use in the FM-CW radarfront-end portion shown in FIG. 15;

FIG. 18 shows an equivalent circuit of the FM-CW radar front-end portionshown in FIG. 17;

FIG. 19 shows another example of the construction of a mixer portionshown in FIG. 15;

FIGS. 20(A) and 20(B) show another example of the construction of themixer portion shown in FIG. 15;

FIGS. 21(A), 21(B), 21(C) and 21(D) show the positional relationshipbetween the dielectric strip and the strip line;

FIGS. 22(A), 22(B), 22(C) and 22(D) show examples of the placement ofthe circuit board within the nonradiative dielectric line;

FIGS. 23(A) and 23(B) show the relationship between theelectromagnetic-field distribution of the nonradiative dielectric lineand the electromagnetic-field distribution of the strip line;

FIGS. 24(A), 24(B) and 24(C) show the positional relationship betweenthe dielectric strip and the strip line;

FIGS. 25(A) and 25(B) show the construction of the nonradiativedielectric line apparatus for use as oscillator, which nonradiativedielectric line apparatus uses an LSE₀₁ mode;

FIGS. 26(A), 26(B) and 26(C) show the construction of a conventionalnonradiative dielectric line;

FIG. 27 is a partially cutaway perspective view illustrating theconstruction of the conventional nonradiative dielectric line apparatushaving a beam-lead diode mounting section;

FIG. 28 shows the construction of the conventional nonradiativedielectric line apparatus for use as an oscillator;

FIG. 29 shows a calculation model used when the relationship isdetermined between the dimensions, materials of the sections of thenonradiative dielectric line, and the cutoff frequency;

FIG. 30 shows a calculation model used when the dispersion curve and thetransmission loss of the nonradiative dielectric line are determined;

FIG. 31 shows the relation of the cutoff frequency with respect to thecutoff section thickness when the thickness dimension of the circuitboard is varied with the dielectric constant of the circuit board keptconstant;

FIG. 32 shows the relation of the cutoff frequency with respect to thecutoff section thickness when the thickness dimension of the circuitboard is varied with the dielectric constant of the circuit board keptconstant;

FIG. 33 shows the relation of the cutoff frequency with respect to thecutoff section thickness when the thickness dimension of the circuitboard is varied with the dielectric constant of the circuit board keptconstant;

FIG. 34 shows the dispersion curve under predetermined set conditions;

FIG. 35 shows the dispersion curve under the predetermined setconditions;

FIG. 36 shows the dispersion curve under the predetermined setconditions;

FIG. 37 shows the dispersion curve under the predetermined setconditions;

FIG. 38 shows the dispersion curve under the predetermined setconditions;

FIG. 39 shows the dispersion curve under the predetermined setconditions;

FIG. 40 shows the dispersion curve under the predetermined setconditions;

FIG. 41 shows the dispersion curve under the predetermined setconditions;

FIG. 42 shows the dispersion curve under the predetermined setconditions;

FIG. 43 shows the results of the transmission loss under each setcondition;

FIG. 44 shows the results of the transmission loss under each setcondition;

FIG. 45 shows the results of the transmission loss under each setcondition;

FIG. 46 shows the results of the transmission loss under each setcondition;

FIG. 47 shows the electric-field distribution of the normal-typenonradiative dielectric line;

FIG. 48 shows the electric-field distribution of the grooved-typenonradiative dielectric line; and

FIG. 49 shows the electric-field distribution of the nonradiativedielectric line which is of a grooved type and in which a circuit boardis inserted at the intermediate position.

DESCRIPTION OF PREFERRED EMBODIMENTS

The construction of a nonradiative dielectric line apparatus accordingto a first embodiment of the present invention is shown in FIGS. 1 and2.

FIG. 1 is a perspective view illustrating the construction of the mainsection. FIG. 2 is an exploded perspective view of the apparatus shownin FIG. 1. Referring to FIGS. 1 and 2, reference numerals 13 and 14denote conductor plates, a groove being formed on each of the facingsurfaces of the two conductor plates, with dielectric strips 10 and 11whose cross sections are in a rectangular shape being provided on thosegrooves. Reference numeral 12 denotes a circuit board of, for example, afluororesin type, with strip lines 15. To be more precise, strip-linesare formed by these conductor lines, and the conductor plates 13 and 14.Ground conductors 16 are formed on the top surface of the circuit boardas shown in FIG. 2. The strip lines are used to form a coplanar guideformed of a conductor line 17 and the ground conductor 16, and to form aplanar dielectric line in the portion shown at reference numeral 18 bymeans of the circuit board, which is a dielectric, and the groundconductor 16 and the conductor plates 13 and 14. The concept of such aplanar dielectric line has been disclosed in Japanese Patent ApplicationLaid-Open No. 7-69867, and this technology can be applied to the presentinvention. By disposing the circuit board 12 having various conductorfilms formed thereon in this way between the two conductor plates 13 and14 and in such a manner as to be interposed between the dielectricstrips 10 and 11, a nonradiative dielectric line is formed by thedielectric strips 10 and 11, the circuit board 12, and the conductorplates 13 and 14. As will be described later, the spacing between thetwo conductor plates 13 and 14, the thickness dimension of the circuitboard 12, and the dielectric constants of the dielectric strips 10 and11 and the circuit board 12, are determined so as to utilizeelectromagnetic waves of the LSM₀₁ mode. FIG. 5(A) shows theelectromagnetic-field distribution of the LSM mode in this case.However, the illustration of the upper and lower conductor plates isomitted. In FIG. 5(A), the solid lines indicate lines of electric force,and the dotted lines indicate lines of magnetic force. Although theelectromagnetic-field distribution varies according to the dielectricconstant of the circuit board and the dielectric constant of thedielectric strip, since basically the LSM mode is a mode in which themagnetic field is parallel to the boundary surface between thedielectric strip and air, the strip lines 15 shown in FIG. 2 and theelectromagnetic wave are coupled to each other.

Next, the construction of a nonradiative dielectric line apparatusaccording to a second embodiment of the present invention is shown inFIGS. 3 and 4.

FIG. 3 is a perspective view illustrating the construction of the mainsection. FIG. 4 is an exploded perspective view of the apparatus shownin FIG. 3. In FIGS. 3 and 4, reference numerals 13 and 14 denoteconductor plates, a groove being formed in each of the facing sides ofthe two conductor plates, with the dielectric strip 10 whose crosssection is rectangular being fitted into those grooves. The circuitboard 12 is disposed between the conductor plates 13 and 14 and parallelto the two conductor plates. For example, a projection portion (notshown) may be provided in the conductor plate 13, and the circuit board12 secured to the projection portion by screws, with the circuit board12 being secured in a predetermined posture at a predetermined position.The circuit board 12 has strip lines 15 similar to those in the firstembodiment. FIG. 5(B) shows the electromagnetic-field distribution ofthe LSM mode in this case. However, also in this case, the illustrationof the upper and lower conductor plates is omitted. In FIG. 5(B), thesolid lines indicate lines of electric force, and the dotted linesindicate lines of magnetic force. Even if the circuit board 12 is notinterposed between the two dielectric strips as described above, sincethe magnetic field of the LSM₀₁ mode leaks outside from the boundarysurface between the dielectric strip 10 and the air between theconductor plates 13 and 14, the magnetic field and the strip line 15 aremagnetically coupled to each other.

Next, the construction of a nonradiative dielectric line apparatus foruse as an oscillator according to a third embodiment of the presentinvention is shown in FIGS. 6(A) and 6(B). FIG. 6(B) is a front viewwhen seen from the output end side, and FIG. 6(A) is a top plan view inwhich an upper conductor plate is removed. In FIGS. 6(A) and 6(B),reference numerals 13 and 14 denote conductor plates which constitutethe lower housing and the upper housing, respectively, with thedielectric strip 10 being mounted at a predetermined position betweenthe housings. As a result, the dielectric strip 10, and the internalsurfaces of the conductor plates 13 and 14, form a nonradiativedielectric line. Further, the circuit board 12 is secured to theconductor plate 13 by screws. Provided on the circuit board 12 are thestrip line 15 and a conductor pattern 20 which forms an RF choke. A Gunndiode 19 is secured to the conductor plate 13 by screws, with itsterminals being wire-bonded to the strip line 15 and the conductorpattern 20. Further, a bias terminal 21 is mounted on the conductorplate 13, and the end of the bias terminal 21 within the interior of theconductor plate 13 is lead-connected to the end portion of the conductorpattern 20. In this construction, by applying a DC bias to the Gunndiode 19, the Gunn diode 19 oscillates, its oscillation signal ispropagated through the strip line 15, the strip line 15 and theabove-described dielectric line are coupled to each other, and theoscillation signal will be propagated through the nonradiativedielectric line.

Next, the construction of another nonradiative dielectric line apparatusfor use as an oscillator according to a fourth embodiment of the presentinvention is shown in FIG. 7. Unlike the third embodiment, the circuitboard 12 is interposed between the two dielectric strips 10 and 11. Thestrip line 15 is provided on the circuit board 12, and the terminals ofthe Gunn diode 19 provided within the block 200 are connected to thestrip line 15. The strip line 15 penetrates into the interior of thefacing surfaces of the two dielectric strips 10 and 11, and thenonradiative dielectric line is formed from the dielectric strips 10 and11, the circuit board 12, and the conductor plates 13 and 14. Thus, theoscillation signal of the Gunn diode 19 is propagated to theabove-described line through the strip line 15.

Next, the construction of a nonradiative dielectric line apparatus foruse as an oscillator including a modulator according to a fifthembodiment of the present invention is shown in FIGS. 8(A) and 8(B). InFIGS. 8(A) and 8(B), FIG. 8(B) is a side view seen from the side where amodulated signal is outputted, and FIG. 8(A) is a top plan view in whichthe upper conductor plate is removed. In FIGS. 8(A) and 8(B), thedielectric strips 10 and 11 are provided at predetermined positions onthe conductor plates 13 and 14 which act as the upper and lowerhousings, respectively. The circuit board 12 is secured to the conductorplate 13 by screws. Further, a DC terminal 28 for a varactor diode and aDC terminal 27 for a Gunn diode are provided on the conductor plate 13.Provided on the circuit board 12 are the strip line 15, conductorpatterns 20 forming RF chokes, and electrodes 23 and 24. Further, theGunn diode 19 is secured to the conductor plate 13 by screws, with itsterminals being connected to the strip line 15 on the surface of thecircuit board. Further, a varactor diode 29 is connected between thestrip line 15 and one of the conductor patterns 20. Furthermore, theelectrode 23 is connected by a lead to the DC terminal 27 for receivinga bias, and the electrode 24 is connected by a lead to the modulationinput terminal 28. With this construction, by inputting a modulationsignal between the modulation terminal 28 and the bias terminal 27 andapplying a high DC voltage between the bias terminal 27 and ground, theGunn diode oscillates, and its oscillation frequency varies according tothe electrostatic capacity of the varactor diode. The oscillation signalis propagated to the nonradiative dielectric line through the strip line15 and to the output side seen in FIG. 8(B).

Next, the construction of a nonradiative dielectric line apparatus foruse as a terminator according to a sixth embodiment of the presentinvention is shown in FIG. 9. FIG. 9 is an exploded perspective viewillustrating a pattern provided on the circuit board 12. A resistor film30 is formed in a tapered shape at a position where the resistor film isinterposed between the dielectric strips 10 and 11 as shown in thefigure. When the circuit board 12 is positioned in such a manner as tobe interposed between the dielectric strips 10 and 11 and the conductorplates 13 and 14, a nonradiative dielectric line is formed. Theelectromagnetic waves which propagate through the line are coupled tothe resistor film 30, and the energy of the electromagnetic wave isconsumed by the resistor film 30, eliminating reflection in thedirection of the incident end.

FIG. 10 is an exploded perspective view illustrating the construction ofanother nonradiative dielectric line apparatus for use as a terminatoraccording to a seventh embodiment of the present invention. Unlike theembodiment shown in FIG. 9, the resistor film is formed in areas beyondthe facing surfaces of the dielectric strips 10 and 11. As a result, theresistor film is coupled also with the electromagnetic wave distributedin the vicinity of the dielectric strip, and thus the electromagneticwaves can be attenuated more effectively.

FIGS. 11(A) and 11(B) show the construction of a nonradiative dielectricline apparatus for use as a terminator according to an eighth embodimentof the present invention. FIG. 11(A) is an exploded perspective view inwhich a conductor plate 14 together with the upper dielectric strip 11are separated. FIG. 1(B) is a partial exploded perspective view showingthe circuit board 12 removed from the lower conductor plate 13. As shownin the figures, a resistor film 30 is formed on the upper side of thedielectric strip 10, and an opening portion 31 is formed in the circuitboard 12 so as to avoid that portion where the resistor film is formed.As a result, even if the film thickness of the resistor film 30 islarge, the surface of the circuit board 12 can be made substantiallyflat, making it possible to place the upper dielectric strip 11 on andin close contact with the circuit board 12. This resistor film 30 isformed by printing a resistor paste on the dielectric strip, or byaffixing a resistor sheet in a tape shape on the dielectric strip.

Next, the construction of a nonradiative dielectric line apparatus foruse as an attenuator according to a ninth embodiment of the presentinvention is shown in FIGS. 12(A) and 12(B). FIG. 12(B) is a side viewseen from the side where an electromagnetic wave is incident, and FIG.12(A) is a top plan view in which the upper conductor plate 14 whichconstitutes the upper housing is removed. In FIGS. 12(A) and 12(B), aresistor film 30 is formed on the circuit board 12 in a tapered shape asshown in FIG. 12(A). As a result, a nonradiative dielectric line isformed by the dielectric strip 10, and the conductor plates 13 and 14.The electromagnetic waves which propagate through the line are coupledto the resistor film 30, and the energy of the electromagnetic wave isconsumed gradually by the resistor film 30. As a result, this apparatusworks as an attenuator.

Next, the construction of a nonradiative dielectric line apparatus whichworks as a directional coupler according to a tenth embodiment of thepresent invention is shown in FIGS. 13 and 14. FIG. 13 is an explodedperspective view of the apparatus. Two dielectric strips 10a and 10b areprovided on the upper conductor plate 13 and two dielectric strips 11aand 11b are provided on the lower conductor plate 14, with the circuitboard 12 being interposed between them and assembled. The strip lines 15are provided at intervals of 1/4 waveguide length on the circuit board12. With this circuit board 12 being interposed between the upper andlower conductor plates 13 and 14, two nonradiative dielectric lines areformed by the dielectric strips 10a, 10b, 11a, and 11b, the circuitboard 12, and the conductor plates 13 and 14, and the strip lines 15 areplaced in such a manner as to cross the two dielectric lines.

FIG. 14 shows the relationship between the two nonradiative dielectriclines and the strip lines. In a case in which two or more strip lines a,b and c are provided at intervals of 1/4 waveguide length with respectto two dielectric strips as shown in the figure, most of the waves whichenter from (1) exit in part to (2), and the other part of the wavesleaks to the dielectric strip on the right through the three strip linesa, b and c. In this arrangement, since all waves which exit to (4) andwhich pass through any strip line are out of phase by the same phaseangle, the waves are synthesized so as to be in phase. However,regarding the waves which exit to (3), the waves which pass through themiddle strip line (e.g., a strip line b) are delayed in comparison withthe waves which pass through the front strip line (e.g., a strip line a)by a phase angle (180 degrees) corresponding to λg/4+λg/4=λg/2.Therefore, the synthesized waves cancel each other, so no wave appearsin the direction of (3).

As a result, the nonradiative dielectric line apparatus works as adirectional coupler.

Next, the construction of a nonradiative dielectric line apparatus whichworks as an FM-CW radar front-end portion according to an eleventhembodiment of the present invention is shown in FIGS. 15(A) and 15(B),and FIG. 16.

FIG. 15(A) shows the internal surface of a conductor plate 14 serving asan upper housing. FIG. 15(B) is a plan view showing a circuit board 12which is located on a conductor plate 13 serving as a lower housing.Referring to FIGS. 15(A) and 15(B), provided at predetermined positionsof the conductor plates 13 and 14 serving as lower and upper housings,respectively, are dielectric strips 10a, 10b, 10c, 10d, 10e, 11a, 11b,11c, 11d, and lie in mutually facing patterns of mirror symmetry. Thecircuit board 12 is interposed between these conductor plates 13 and 14.Various conductor film patterns and resistor film patterns which aremade to work as an oscillator, a terminator and a mixer, respectively,are formed on the circuit board 12. Of these, the construction of theoscillator portion is the same as that shown in FIGS. 8(A) and 8(B).Further, the construction of the terminator portion is the same as thatshown in FIG. 9 or FIG. 10. In the mixer portion of the circuit board12, various arrangements of a conductor pattern 20 serving as an RFchoke, a conductor plate 25 for RF matching, and the strip line 15 areformed. A Schottky barrier diode 26 is mounted on the conductor plate25. The two dielectric strips 10a and 11a are positioned in such amanner as to sandwich the conductor plate 25.

With this construction, a nonradiative dielectric line is formed by thedielectric strips 10a and 11a, the circuit board 12, and the conductorplates 13 and 14. The electromagnetic wave RF+LO (see FIG. 16) whichpropagates through the line and the conductor plate 25 are coupled toeach other, RF current flows through the Schottky barrier diode 26, anintermediate frequency is generated due to the nonlinearity of thediode, and this signal is taken out at an IF output terminal 22 throughthe conductor pattern 20. The RF signal and the LO signal are blocked bythe conductor pattern 20, and not output at the IF output terminal.

Each of the conductor plates 13 and 14 is provided with a ferrite disk32 inside and a magnet (not shown) outside. The dielectric strips 10d,10c, 10e, 11d, 11c, and 11e, the ferrite disk 32, and the magnetconstitute a circulator. This circulator, and the terminator formed ofthe dielectric strips 10e and 11e, and the resistor film 30 constitutean isolator. That is, the waves transmitted from the oscillator aretransmitted in the direction of the dielectric strips 10c and 11c, andany reflection waves are consumed by the resistor film 30 and are hardlyreturned to the oscillator.

The section between the dielectric strips 10b and 11b, and dielectricstrips 10c and 11c, and the section between the dielectric strips 10aand 11a, and dielectric strips 10c and 11c work as a coupler. As aresult, the transmission waves of RF+LO are input to the above-mentionedmixer.

The end portions of the dielectric strips 10c and 11c are connected to atransmission antenna (not shown), and the end portions of the dielectricstrips 10a and 11a are connected to a receiving antenna (not shown). Asthese antennas, an antenna in which a dielectric strip is formed into arod shape, and a leakage wave NRD guide antenna are used.

FIG. 16 is an equivalent circuit diagram of the apparatus shown in FIGS.15(A) and 15(B). When the oscillation frequency of the oscillator ismodulated by a triangular wave as shown in the figures, a beat frequencysignal, which is representative of the distance from the antenna to areflection object and the relative speed thereof, is output as an IFsignal from the mixer, and by processing the IF signal, the distance tothe object and the relative speed are determined.

Next, the construction of an instrument for measuring thecharacteristics of the circuit board for use in the above-describedFM-CW radar front-end portion is shown in FIGS. FIGS. 17(A) and 17(B),and FIG. 18.

FIG. 17(A) shows the internal surface of a conductor plate 14 serving asan upper housing. FIG. 17(B) is a plan view of a conductor plate 13serving as a lower housing. Provided at predetermined positions of theconductor plates 13 and 14 are dielectric strips boa, 10c, 11a, 11c inmutually facing patterns of mirror symmetry. Unlike that shown in FIGS.15(A) and 15(B), here, the dielectric strips 10b and 11b whichconstitute the coupler, and the dielectric strips 10e and 11e whichconstitute the circulator are not provided. The circuit board 12 isinterposed between these conductor plates 13 and 14. FIG. 18 is anequivalent circuit diagram in such a state.

As described above, a measuring instrument is connected to the endportions of the dielectric strips 10c and 11c via the nonradiativedielectric line (the waveguide converter). As a result, it is possibleto measure the characteristics solely of the oscillator. Further, byconnecting a test signal generator to the end portions of the dielectricstrips 10a and 11a via the nonradiative dielectric line (the waveguideconverter) and by measuring the IF output signal of the circuit board,the characteristics solely of the mixer can be measured.

In the example shown in FIGS. 15(A) and 15(B), a strip line is formedfrom the mixer portion to the end portion of the circuit board. However,for example, as shown in FIG. 19, the strip line may be connected to theIF output circuit and to ground by coaxial cables which go through thelower conductor plate. Further, as shown in FIG. 20(A), it may bepossible to form a pattern for connection to ground on the circuit boardbeforehand and make connection to ground by making this portion contacta projection portion 14' provided on the conductor plate 14 as shown inFIG. 20(B).

As shown in FIGS. 21(A) and 21(C), the above-described embodimentsdescribe examples in which a strip line is positioned close to adielectric strip or a part of a strip line is made to penetrate into theinterior of the dielectric strip. In addition to this, as shown in FIG.21(B), it may be possible to bring the end portion of the dielectricstrip and the end portion of the strip line into alignment with eachother. Further, as shown in FIG. 21(D), it may be possible to connectstrip lines by placing them symmetrically with respect to the dielectricstrip.

Further, the above-described embodiments describe examples in which acircuit board is positioned in such a manner as to be interposed betweenseparated dielectric strips. In addition, for example, as shown in FIG.22(A), it may be possible to insert the end portion of the circuit board12 into the side portion of the dielectric strip.

Further, the above-described embodiments describe examples in which arelatively large circuit board having substantially the same size asthose of the upper and lower conductor plates is used. In addition, forexample, as shown in FIG. 22(B), it may be possible to bring the circuitboard 12 close to, or to insert it into, only a part of the dielectricstrip.

Further, although the above-described embodiments describe examples inwhich the circuit board 12 is positioned at a substantially intermediateposition between two conductor plates, as shown in FIG. 22(C), it may bepossible to vary the distance from the conductor plates as required.

In addition, in some of the above-described embodiments, the circuitboard 12 is positioned in close contact between the dielectric stripswhich are separated to be upper and lower dielectric strips. However,for example, as shown in FIG. 22(D), it may be possible for the circuitboard 12 to be separated from one or both of the dielectric strips.

In all the embodiments described up to this point, a nonradiativedielectric line apparatus employing an LSM₀₁ mode is described. However,the present invention can also be applied to a line employing an LSE₀₁mode as well. An example thereof will be described below with referenceto FIG. 23(A) to FIG. 25(B).

FIG. 23(A) shows the electromagnetic-field distribution of the LSE₀₁mode. However, the illustration of the upper and lower conductor platesis omitted. FIG. 23(B) shows the electromagnetic-field distribution ofthe strip line.

Referring to FIGS. 23(A) and 23(B), the solid lines indicate lines ofelectric force, and the dotted lines indicate lines of magnetic force.Although the electromagnetic-field distribution varies according to thedielectric constant of the circuit board and the dielectric constant ofthe dielectric strip, since basically the LSE mode is a mode in whichthe magnetic field is parallel to the end surface of the strip line, thedielectric strip and the strip line 15 which extends in the transmissiondirection thereof are electromagnetically coupled to each other.

FIGS. 24(A), 24(B) and 24(C) show the positional relationship betweenthe dielectric strip and the strip line. When the strip line ispositioned in such a manner as to be close to the end portion of thedielectric strip or to penetrate into the inside of the dielectricstrip, the nonradiative dielectric line formed of the dielectric stripand the conductor plates above and below the dielectric strip and thestrip line are coupled to each other in the LSE₀₁ mode.

FIGS. 25(A) and 25(B) show the construction of a nonradiative dielectricline apparatus for use as an oscillator. FIG. 25(A) is a top plan viewin which the upper conductor plate is removed, and FIG. 25(B) is asectional view thereof. Referring to FIGS. 25(A) and 25(B), referencenumerals 13 and 14 denote conductor plates which constitute the lowerhousing and the upper housing, respectively, with the dielectric strips10 and 11 being mounted at respective predetermined positions. As aresult, the dielectric strip 10, and the internal surfaces of theconductor plates 13 and 14 form a nonradiative dielectric line. Thecircuit board 12 is fixedly secured to the conductor plate 13, and thestrip line 15 and the conductor pattern 20 which serves as an RF chokeare provided on the circuit board 12. The Gunn diode 19 is secured tothe conductor plate 13 by screws with its terminals being wire-bonded tothe strip line 15 and one end of the conductor pattern 20. Further, abias terminal 21 is mounted on the conductor plate 13, and its end inthe interior of the conductor plate 13 is connected to the end of theconductor pattern 20. With this construction, by applying a DC bias tothe Gunn diode 19, the Gunn diode 19 oscillates, its oscillation signalis propagated through the strip line 15, the strip line 15 and theabove-described dielectric line are connected to each other, and thesignal is propagated through the nonradiative dielectric line.

Although in each of the above-described embodiments the grooved-typenonradiative dielectric line shown in FIG. 26(B) is formed, the sameapplies to the normal-type nonradiative dielectric line shown in FIG.26(A) or the window-type nonradiative dielectric line shown in FIG.26(C) as well.

A description will be given below of the analysis results in a case inwhich the dimensions and the materials of the sections of various typesof nonradiative dielectric line are varied when the propagationfrequency of the circuit is set at 60 GHz.

Initially, as shown in FIG. 29, the cutoff frequency is determined in acase in which the total thickness is denoted as y when a circuit boardis inserted into that portion (hereinafter referred to as a cutoffportion) where there is no dielectric strip from among the nonradiativedielectric line, the board thickness is denoted as t, and the dielectricconstant of the board is denoted as εr.

FIGS. 31 to 33 show the relationship between the cutoff portionthickness y and the cutoff frequency when the board thickness t isvaried by using boards of mutually different dielectric constants. FIG.31 shows an example in which the dielectric constant εr of the circuitboard is set at 2.5. For example, when the board thickness t is 0.4 mm,the cutoff portion thickness y when a design is made with, for example,the cutoff frequency of the cutoff portion being set at 66.7 GHz is 1.7mm. FIG. 32 shows an example in which the dielectric constant εr of thecircuit board is set at 3.5. For example, when the board thickness t is0.2 mm, the cutoff-portion thickness y at which the cutoff frequencybecomes 66.7 GHz is 1.75 mm. FIG. 33 shows an example in which thedielectric constant εr of the circuit board is set at 10. When the boardthickness t is 0.1 mm, the cutoff-portion thickness y at which thecutoff frequency of the cutoff portion becomes 66.7 GHz is 1.45 mm.

Generally speaking, in comparison with a normal-type nonradiativedielectric line in which a circuit board is not inserted, when a circuitboard having a certain dielectric constant is inserted into its cutoffportion, the cutoff frequency of the electromagnetic wave havingpolarized planes parallel to the upper and lower conductor platesdecreases. For this reason, in order to obtain the predetermined cutofffrequency of 66.7 GHz, it is necessary to lessen the space between theupper and lower conductor plates of the cutoff portion. The cutoffportion thickness y and the grooved depth g at which the cutofffrequency of the cutoff portion becomes cutoff frequency becomes 66.7GHz, which are determined from the results of FIGS. 31 to 33, are shownin the table below.

                  TABLE 1                                                         ______________________________________                                                   Board Thickness t mm!                                              y mm! (g mm!)                                                                              0.1        0.2      0.4                                          ______________________________________                                        εr                                                                             2.5     2.1(0.075) 1.95(0.15)                                                                           1.7(0.275)                                          3.5     2.0(0.125) 1.75(0.25)                                                                           1.45(0.4)                                           10      1.45(0.4)                                                    ______________________________________                                    

where the grooved depth g is determined on the basis of g=(2.25-y)/2.

Next, for the model of FIG. 30, the dispersion curve and thetransmission loss are determined on the basis of the parameters of thefollowing Table 2.

                  TABLE 2                                                         ______________________________________                                                                                Electric-                             Line             Board      Disper-                                                                             Trans-                                                                              field                                      Struc-          Thick-     sion  mission                                                                             Distribu-                         No.  ture    g(mm)   ness  εr                                                                         Curve Loss  tion                              ______________________________________                                        1    Normal  0.00               FIG. 34     FIG. 47                           2    Groov-  0.15               FIG. 35                                       3    ed      0.30               FIG. 36     FIG. 48                           4            0.45               FIG. 37                                       5            0.30    0.1   2.5  FIG. 38                                                                             FIG. 43                                                                             FIG. 49                           6                          3.5  FIG. 39                                       7                    0.2   2.5  FIG. 40                                                                             FIG. 44                                 8                          3.5  FIG. 41                                       9                    0.3   2.5        FIG. 45                                 10                         3.5                                                11                   0.4   2.5        FIG. 46                                 12                         3.5                                                13           0.45    0.1   10   FIG. 42                                                                             FIG. 43                                 ______________________________________                                    

where the dielectric constant of the dielectric strip is 2.04, tanδ is1.5×10⁻⁴, and tanδ of the circuit board is 0.01 to 0.0001.

It can be seen from FIGS. 34 to 37 that when the dispersion curves ofthe normal-type nonradiative dielectric line and the grooved-typenonradiative dielectric line are compared with each other, as thegrooved depth g becomes greater, the lowest-order mode varies from theLSE₀₁ mode to the LSM₀₁ mode. Here, since the LSM₀₁ mode and the LSE₀₁mode overlap each other between g=0.15 and 0.30 mm, it is necessary toavoid a design in which the grooved depth g falls within this range.Further, since at g=0.45 mm, the difference between the LSM₀₁ mode andthe LSE₀₁ mode becomes wider, transmission in the single mode of theLSM₀₁ mode is made possible by determining the groove depth g.

Further, it can be seen from the results of FIGS. 38 to 41 that even ifa circuit of a low dielectric constant, for example, εr=2.5 or 3.5, isinserted, there is no large change in the dispersion curve, and theinfluence upon the transmission characteristic is small. However, acomparison between the model (FIG. 36) in which no board is inserted andthe model (FIG. 38) in which a board is inserted shows that theinsertion of the board causes the cutoff frequency to decrease. However,as described above, the amount of the decrease of the cutoff frequencymay be compensated for by setting the y dimension.

It can be seen from the results of FIGS. 34 to 46 that a practicaltransmission line whose transmission loss is 20 dB/m or less can beformed through the use of low dielectric constant εr=2.5 to 3.5, theboard thickness t=0.1 to 0.3 mm, and the dielectric tangent tanδ=2×10⁻³(corresponds to thereof the board of a fluororesin type) of the circuitboard.

Many different embodiments of the present invention may be constructedwithout departing from the spirit and scope of the present invention. Itshould be understood that the present invention is not limited to thespecific embodiments described in this specification. To the contrary,the present invention is intended to cover various modifications andequivalent arrangements included within the spirit and scope of theinvention as hereafter claimed. The scope of the following claims is tobe accorded the broadest interpretation so as to encompass all suchmodifications, equivalent structures and functions.

What is claimed is:
 1. A nonradiative dielectric line apparatus which isan integrated circuit having nonradiative dielectric lines positioned inparallel to each other in which a dielectric strip is provided betweentwo conductors, wherein a circuit board having a conductor film or acircuit element together with a conductor film provided thereon isdisposed between said two conductors and substantially in parallel tothe conductors, and the conductor film or the circuit element providedon said circuit board is brought close to or is made to penetrate intosaid dielectric strip in order to couple said conductor film or saidcircuit element to said nonradiative dielectric line.
 2. A nonradiativedielectric line apparatus according to claim 1, wherein an oscillationelement, and a conductor line for transmitting oscillation signals ofthe oscillation element are provided on said circuit board, and theconductor line is brought close to or is made to penetrate into saiddielectric strip in order to transmit said oscillation signals to saidnonradiative dielectric line.
 3. A nonradiative dielectric lineapparatus according to claim 1, wherein a resistor film is formed onsaid circuit board, and the resistor film is brought close to or is madeto penetrate into said dielectric strip in order to attenuate theelectromagnetic wave propagated through said nonradiative dielectricline.
 4. A nonradiative dielectric line apparatus according to claim 1,wherein two of said dielectric strips are provided side by side to formtwo nonradiative dielectric lines, a plurality of conductor filmpatterns are provided on said circuit board at intervals of 1/4 of awaveguide length, the plurality of conductor film patterns providedbetween said two dielectric strips, and the plurality of conductor filmpatterns are brought close to or are made to penetrate into said twodielectric strips in order to couple said two nonradiative dielectriclines to each other.
 5. An instrument for measuring characteristics of acircuit board, said instrument comprising:two conductors positioned inparallel to each other, a dielectric strip provided between the twoconductors, and a circuit board housing section for housing a circuitboard having a conductor film or a circuit element together with aconductor film provided thereon is disposed between said two conductorsand substantially in parallel to the conductors, wherein the conductorfilm or the circuit element provided on said circuit board is broughtclose to or is made to penetrate into said dielectric strip in order tocouple said conductor film or said circuit element to said nonradiativedielectric line; said circuit board housing section being disposedbetween said two conductors, wherein the characteristics of said circuitboard are measured via said dielectric strip with the circuit boardbeing housed in the circuit board housing section.